The present invention relates to an injection plug device for injecting concrete repairing agent into voids or cracks formed in a concrete structure and to a connector to be attached to such an injection plug device.
A typical concrete wall consists of an inner concrete body and an outer mortar layer measuring 2 cm-3 cm in thickness for covering and decorating the rough surface of the inner concrete body. Degradation caused by aging of the concrete may cause separation of the mortar layer from the surface of the concrete body, forming voids or cracks, sometimes called "floating areas," between the surface of concrete body and the mortar layer. These cracks are often 0.2 mm-1 mm wide.
As a typical method for repairing such a concrete wall with voids or cracks formed inside, the following repairing method is known. At first, an injection hole is formed in the wall so as to establish fluid communication between an area outside of the concrete wall and the voids inside. Then, an injection plug device will be inserted and fixed into the injection hole. Next, concrete repairing agent such as epoxy resin or polymer cement will be injected into the injection hole through the injection plug device to fill the voids. The repairing agent hardens or cures within the voids and provides a bond between the concrete body and mortar layer.
The injection plug devices described above are divided into two categories. One, a non-detachable type, is buried inside the repaired concrete wall. Bolt type devices which are hammered into the concrete wall are typical of these devices. The other is a detachable type, which may be detached and recovered from the repaired concrete wall. Detachable type injection plug devices are preferred non-detachable type injection plug devices often damage the finish and aesthetic appearance of the wall, because the top portion of the device usually protrudes from the surface of the repaired concrete wall.
The detachable type injection plug device described above preferably can be attached firmly to the concrete wall while concrete repairing agent is injected and before it is solidified, and can be detached easily from the concrete wall after the injected repairing agent is solidified. From this point of view, detached type injection plugs that are attached to the wall using adhesives are not preferred, because laborious and time consuming work is required to detach the devices from the concrete wall and to remove residual adhesives that makes spots on the wall to spoil a fine view of the wall.
An injection plug device which does not require such laborious work for removing residual adhesives from a concrete wall is disclosed by Japanese Utility Model Application S63-148748.
Further, detachable type injection plug devices often cannot be removed from a concrete wall until the injected concrete repairing agent is almost solidified so as to prevent back flow through the injection hole when the injection plug device is detached. As a result, laborious and time consuming work is often required to remove partially solidified repairing agent from inside of the plug device after the device has been detached from the concrete wall.
Furthermore, methods for preventing back flow of concrete repairing agent from the concrete wall during injection are divided into two categories. One category is characterized by the use of a check valve mechanism inside the plug device, and the other category is categorized by a check valve mechanism inside a hose, or connector which connects the hose to the injection plug device. It is preferable to set up a check valve mechanism inside the plug device, as this reduces the time required to complete an entire repairing operation in which a plurality of injection holes are formed on a concrete wall. This is so because it reduces the number of hoses and connectors that are required to complete the operation.
To eliminate the laborious work of removing partially solidified repairing agent from inside the injection plug device, it may be possible to make the plug device disposable by providing it with a simple and inexpensive structure. However, where it is desirable to use a detachable injection plug device which includes a back flow prevention mechanism, it is difficult to achieve an inexpensive design structure. Therefore, as is disclosed in a prior Japanese Patent Application (H4-75,176), an injection plug device of simple and inexpensive design was invented by the present inventors which has a coaxial double structure comprising an outer pipe member, and an inner disposable pipe member which is attached and detached easily to and from the outer pipe member.
The injection plug device according to the Japanese Patent Application described above has a substantial advantage in that it is not expensive and can be used very easily to reduce the time required for repairing operations. This is so because only the inner pipe member is made disposable. However, this injection plug device has relatively large outer diameter, about 20 mm, because it has a coaxial double structure. This requires an increase in diameter of the injection hole to be formed in a concrete wall. Further, such a injection hole must be treated so as not to spoil the appearance of the repaired concrete wall. However, the increase of diameter of the injection hole makes it difficult for the injection hole to be treated sufficiently to avoid damaging the finish of the concrete wall.
A connector for detachably connecting a tip portion of an injection hose to the injection plug device was invented by the present inventors and was disclosed in Japanese Patent Application H7-106,979 (U.S. patent application Ser. No. 08/628,856). This connector has a relatively complicated structure in which a path bending at a right angle is formed inside a plastic block to make injected concrete repairing agent flow through it. A needle valve is provided at the bend of the path to open and close the path. Since the structure of the connector of the prior art is relatively complicated, it has a problem in that it becomes difficult to remove partially solidified repairing agent from inside of the connector.